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应用Li-6 400光合测定系统研究了贡嘎山地区不同海拔黄背栎(Quercus pannosa)幼树的光合生理特性。结果表明:(1)在8月晴天,不同海拔生长的黄背栎叶片净光合速率日变化均呈比较平稳的单峰曲线,无光合午休现象,随着海拔的升高,叶片净光合速率、蒸腾速率和水分利用效率均降低,而叶片气孔导度增加,有利于高海拔地区植物光合作用气体交换;(2)不同海拔试验点叶片净光合速率对光合辐射的响应有较大的差异,叶片光补偿点为39.16~68.06μmol/(m2.s),光饱和点为1 124.78~1 754.88μmol/(m2.s),表观光量子利用效率为0.028 12~0.031 73。随着海拔的升高,叶片光补偿点、光饱和点和最大净光合速率增加;(3)叶片CO2补偿点为68.47~105.21μmol/mol。随着海拔的升高,CO2补偿点降低,有利于植物对高海拔地区低CO2分压环境的适应。CO2饱和点在700μmol/mol左右,羧化效率为0.035~0.038。
The photosynthetic characteristics of saplings of Quercus pannosa at different altitudes in Gongga Mountain were studied using Li-6 400 photosynthesis system. The results showed as follows: (1) On the sunny day of August, the net photosynthetic rate of Quercus variabilis growing at different altitudes showed a relatively steady single peak curve with no photosynthesis at lunch break. With the elevation increasing, the net photosynthetic rate, Transpiration rate and water use efficiency decreased, while leaf stomatal conductance increased, which was in favor of gas exchange of plant photosynthesis at high altitude. (2) Leaf net photosynthetic rate responded differently to photosynthetic radiation at different altitudes, The light compensation point was 39.16 ~ 68.06μmol / (m2.s), the light saturation point was 1 124.78 ~ 1 754.88μmol / (m2.s), and the apparent photon quantum efficiency was 0.028 12 ~ 0.031 73. With the elevation increasing, leaf light compensation point, light saturation point and maximum net photosynthetic rate increased. (3) Leaf CO2 compensation point was 68.47 ~ 105.21μmol / mol. As the elevation increases, the CO2 compensation point decreases, which is beneficial to the adaptation of plants to the low CO2 partial pressure environment at high altitude. CO2 saturation point is about 700μmol / mol, carboxylation efficiency is 0.035 ~ 0.038.